Inductive components are needed on integrated circuits for a wide variety of applications. Inductors formed on radio frequency (RF) or microwave frequency integrated circuits generally require a large amount of die space to achieve any significant inductance. In addition to substantial space consumption, when compared to typical transistors, resistors, and capacitors, the performance of integrated inductors tend to be poor. Inductors are often implemented on integrated circuits using spiraled conductor lines. Planar spiral inductors are easily fabricated, requiring only a single patterned metal layer, which tends to be space efficient. U.S. Pat. No. 5,396,101, issued to Shiga on Mar. 7, 1995, for an Inductance Element, describes an integrated spiral inductor that incorporates a core portion to increase inductance and/or to reduce space consumption.
Despite these advances, inductors integrated on integrated circuit substrates, such as silicon and gallium arsenide, still consume substantial space for radio frequency and microwave frequency applications. It is therefore desirable to obtain a better performing inductor for integrated circuit applications.